Ignition magneto



June 23, 1925. 1,543,347

E. O. TURNER ET AL N Ulli/NIMH June 23, 1925. 1,543,347

E. o. TURNER ET Al.

IGNITION MAGNETO Filed nec. 21,1922 2 sheets-sheet 2 Patented 23, 1925. I

A1,543,341 PATENT or-"Ficay nnNnsT o. Tum AND nnwAaD n. TUPPIIN, or nIaIIINGIIAn, ENGLAND, Ass IGNoas To m nnITIssI LIGHTING AND IGNITION coIIrANY, LIMITED, or sIav IIINGIIAII, nrGLAND, A saITIsII coNrANY.

IGNITION IIAGNE'm.

Application lied December 21, 1922. serial No. 608,180.

To all whom it may concern.'

Be it known that we, ERNEST OWEN TUR- Nnn and EDWARD BnowNn TUPPEN, both subjects of the King of Great Britain, residing, respectively, at 35 Mayfield Road, Moseley Birmingham, in the count of Warwick, England, and 96 Court ane, Erdington, Birmingham, in the county of Warwick, England, have invented certain l0 new and useful Improvements in or Relating to Ignition Magnetos, of which the following is a specification.

This invention relates to ignition magnetos for internal combustion en `nes, said magnetos being of the type in w ich a rota magnet is employed in conjunction with a ed amature, and has special reference to the mechanical construction of the magnet rotors for ignition magnetos of the type described in the specification of our co-pending patent application Serial No. 562725 filed 22nd May 1922 and in particular to rotors of the type in which solid magnets with pole shoes of laminated soft iron are 25 em loyed.

- ccording to the present invention a magnet rotor for i ition magnetos of the type referred to an having pole shoes of laminated construction is provided with one or 80 more plates interleaved at suitable intervals with the iron laminations constituting the said pole shoes, the said interleaving plates being made of such material or constructed in such manner as to prevent passage of the 85 flux in an undesirable direction. Preferably the interleaving plates are made of nonmagnetic material such as brass or other non-magnetic substance, but if desired the said lates may be made of iron `or steel in 0 which) latterI case the are rovided with slots or holes suitably ispose so as to avoid the contin ncy of any undue leakage between neig bouring portions of the magnet pole shoes or between two portions of the I magnet between which there may bea difference of magneto-motive-force. By means of this construction the pole shoes ma 'be rigidly fastened in sition with but ittle or no reduction of t eir effective cross sectional area by the space usually occupied by rivets or like fastenmgs.

The magnet may if esired be made up of a number of magnets of correspondingly reduced axial length, a small space being left between each individual magnet for a nonmagnetlc partitlon, which in this case may be made stronger if required, as the portion of the area that otherwise would be takenv up by the magnet is set free, and advanta e of this may e taken by stiifening up t e partition ver considerably if it 1s so de-i sired. The a vantage of the use of the interleaving partitions in the manner described is that the pole shoes are thereby made much more rigid and less of their cross-sectional area need be taken up by rivets or screws.

While in the case of ignition magnets of the type that spark s mmetrically twice per revolution the pole shoes are usually so designed that the pole shoe arcs subtend an angle in the neighbourhood of 90 at the point constltutin the centre round which the said arcs are escribed, in the case of the present invention the pole shoes may be designed so that they subtend any des1red angle, and in particular an angle substantially ess than 90, for example $50 and in this latter case the length of the pole arc of the stator shoes is increased by an amount dependent on the extent to which the afore` said angle has been decreased from the normal angle of 90. By means of this construction the magnetic leakage between the shoe tips and the neighbouring portions of the magnet can be considerably reduced.

The present invention is applicable to devices having various forms of magnet, either straight or curved in such shapes as those of an S or U, and in which the pole shoes, while comprising a number of portions to admit of interleaving with plates of non- Inagnetic material or with suitably constructed iron or steel plates as referred to above have the said portions either of solid or laminated construction.

In order that the invention may be clearly understood and readily carried into effect, the same will now be more fully described with reference to the accompanying drawings, in which Figure 1 shows in elevation and part section a rotor with the pole shoes and interleaving plates.

Figure 2 shows in perspective one form of the non-magnetic discs or laminations.

Figure-3 is a section on the line A B of Figure 1 at right angles to the axis of rotation.

Fi re 4 is a perspective view of the laminat le shoe extensions and the non-magnetic 'scs or laminations shown in Figure 2, the spindles and ma et being removed.

Figures 5, 6, 7 and 8 i lustrate respectively various other cross sectional shapes for the rotary magnet with pole shoes and means of attaching the two ri 'dly together.

Figure 9 shows in e evation a pole shoe superimposed on a non-magnetic interleaving`plate.

igurev 10 shows a separate interleaving plate of another type.

Figures 11 and 12 illustrate two elevations of com lete magnet rotors with the spindles attac ed.

Figure 13 shows an interleaving plate made of magnetic material.

Fi re 14 is a cross sectional view showing t e same interleaving plate as in Figure 13 and in addition the magnet and pole shoes.

Figure 15 shows in elevation and part section a rotor with the pole shoes and interleaving plates but with the magnet made up of a number of individual magnets.

Figure 16 shows in perspective one of the partitions between the individual magnets shown in Figure 15 and Figure 17 shows in perspective one of the non-magnetic interleaving plates inserted between the iron laminations of the magnet pole shoes.

Referring to Figures 1, 2, 3 and 4, the two pole faces of the permanent magnet 1 are arranged to fit closely against the corres onding pole shoes or extensions 3, 3, at t e surfaces 4, 4, so that good magnetic contact is made. These faces also serve as a location for the magnet in a direction at right angles to the axis of rotation. Movement of the magnet in the plane of these faces and at right angles to the axis is prevented by contact which is made with theJ inside of the non-magnetic laminations 7 at the points 5 and 6. Movement of the magnet 1 in an axial direction is prevented by the spindle and flanges 2, 2. In order however to prevent the magnet being positively pressed between the flanges 2, 2, as it is better that all available pressure due to the rivets 9 which hold the end flanges 2, 2 should be concentrated on the iron laminations 3 and brass interleaving plates 7,' a iece of material 12 which will yield slighty under pressure is interposed between the ma et 1 and the flange 2 at one or both In assembling the form of device under consideration, the pole shoes or extensions 3 and the non-magnetic laminations 7 are first assembled as shown in Figure 4; there may Luau? of course be any desired number of laminations 3 and also of the laminations 7. The desired number of laminations 3 and 7 are assembled on the four rivets 8, tightly pressed together, and then the rivets riveted over, In order to ensure that the assembled unit is not distorted during the rivetin o ration a suitable jig ma be provid e number of rivets v8 may be increased or decreased as desired. In order to obtain the best possible contact at the surfaces 4, 4, a machmlng operation such as broaching ma be employed before the magnet is This operation may also serve to true up the surfaces 5 and 6. The correspon portions of the magnet are ground to t e de-l sired size, and the m et 1 is then inserted togieiier with spline gtie din Ilterial 12, the en anges 2 t en in ition. Rivets 9 are then mtas, and whiliispressure is exerted on the end anges these rivets are riveted over. The result is a compact and substantially constructed unit, in which the shoes for the north and south poles of the ma et are held together in a ind of cage. e number of rivets 9 may be increased or decreased as desired, or in lieu thereof screws may be used. In this way the pole shoes or extensions are securely held in the desired position and in close contact with the pole faces of the magnet.

After the rotorv is bled, as shown in Figure 1, the usual finishing o rations may be applied to the spindles an the external surface of the rotor to brin it to the desired diameter. The le s oes or extensions 3 may be design to 've any desired angle between the tips, ang,l if greater accuracy is required than is obtained by the ordinary process of punching, the tips may be convenientl machined after the rotor has been assem led.

In the modification shown in Figure 5 the magnet 1 is shown in section, and the separate laminated pole shoes are shown at 3, 3, the intermediate non-magnetic plates being shown at 7*. The main rivets by which the structure is held together are shown at 81, these rivets occupying butlittle y space of the pole shoes themselves, whilst additional lig t rivets 8 n are also added. A' balance weight held in position by the flanges carryin the spindles at either end of the rotor is siown at 13.

In the alternative forms of construction illustrated by succeeding figures the interleaving plates are formed, similarly to the construction illustrated in Figures 1 to 4, as a kind of ca limiting the motion of the magnet and ho ding to ether the north and south pole shoes in ependently of the flanges at either end.

In the modification shown in pole shoes 3 are formed with a wedge shaped re7the4 slot into which the ends of the S-sha magnet lit, thus preventing sideways 1splacement of the magnet 1 without the necessity of s ially shaping the interleaving plates for t is purpose, an in addition permit-ting the mechanical balance of the device to be more readily attained, so that the addition of an extra. pair of rivets or weights for balancing purposes is rendered unnecessary.

Figure 9 shows the interleaving partitlon 7 in end elevation with front, whilst in the modification shown in Figure 6 a balance weight 13 is inserted in the cage, and further rivets 8111 are also added; these latter rivets 8u1 may be used or omitted as desired. Figure 8 shows a construction in which all rivets except very li ht ones 8x1 through the pole shoes themse ves are dis ensed with, the structure being made su ciently rigid to enable this to be done, The completed magnet rotor embodying the construction referred to in connection with Figure 8 and employing a number of interleaving non-magnetic plates, one of which is illustrated in Figure 10, Ais shown in elevation in Figures 11 and 12, in the case of the latter howeverthe rotor be- -ing turned through an angle of 90 from the position shown in Figure |11.

In the case when the interleaving plates are made of magnetic material as illustrated in Figures 13 and 14, the said plates 7 are made with suitably dis sed holes 14, or slots 15 so as to provi e an iron path of small cross section, the object of the holes or slots being to reduce the cross section of iron path providin a leakage path for magnetic flux, so t at this path becomes readily saturated and undue leakage is hereby prevented from taking place bctween, for example, the north and south poles of the magnet (as on the left-hand side of Figure 14) or between the pole slices 3 and the arch of the magnet (as on the righthand side of Figure 14).

, In the case of' the rotor illustrated in Figure 15 a number of se arate magnets 1 are used instead of the singie permanent magnet 1, shown in Figure 1; between the separate magnets 1 there are interposed support plates 7 made of nonmagnetic material (shown in perspective in Figure 16), whilst at suitable intervals between the iron laminations of the pole shoes there are inserted non-magnetic interleaving plates T (shown in perspective in Figure :1

In all the various constructions of rotor in accordance with ,the present invention the magnet and other components may be so designed and located that the rotor when completely assembled is balanced about its axis of rotation re ardless of the actual centre of gravity o the magnet. On the ole shoes 3, 3, in

neto, said rotor comprising a rotary magedotherhand the magnet may be so designed ce net, separate pole shoes for said magnet, l

said pole shoes comprising a plurality of iron laminations, and interleavlng plates inserted at suitable intervals between the said iron laminations. e

2. A magnet rotor for an ignition magneto, said rotor comprising a rotary magnet, separate pole shoes for said magnet, said pols shoes comprising a plurality of iron lamlnations, and interleaving plates made `of non-magnetic material inserted at suitable intervals' between the said iron laminations. n

3. A magnet rotor for an ignition mag.- neto, saidl rotorcomprisin a rotary magnet, separate pole shoes or said magnet,

lsaid pole shoes comprising a plurality of iron laminations, interleaving plates inserted at suitable intervals between the said iron laminations, and fastening devices to secure the iron laminations and interleaving plates rigidl in position with a minimum reduction o 'the effective cross-sectionaly area of said pole shoes.

4. A magnet rotor for an ignition magneto, said rotor comprisin a rotary magnet,.separate pole shoes or said magnet, said pole shoes comprising a plurality of iron laminations, interleaving plates made of non-magnetic material inserted at suitable intervals between the said iron laminations, and fastening devices to secure the iron laminations and interleaving plates rigidly in position with a minimum reduction of the effective cross-sectional-area of said pole shoes.

5. A magnet rotor for van ignition magneto, said rotor comprising a rotary magnet, separate pole shoes for said magnet, said pole shoes comprising a plurality of iron laminations, and interleaving plates inserted at suitable intervals between the said iron laminations, said interleaving plates each having a continuous periphery forming a bridge between the pole shoes and having le shoes comprising a plurality o and having a suitably shaped aperture to :permit insertion of the magnet, and fastenling devices to secure the iron lannnations and interleaving plates rigidly in position with a minimum reduction of the effective cross-sectional area of said pole shoes.

7. A magnetrotor for an ignition magneto, said rotor comprising a rotary magnet, separate pole shoes Jfor said magnet, said pole shoes comprising a plurality of iron laminations, and interleaving plates inserted at suitable intervals between the said iron laminations, said interleaving plates each having a continuous periphery forming `a bridge between the pole shoes and having an aperture for the insertion of the magnet suitably shaped to prevent the occurrence of lateral movement between the magnet and the pole shoes.

8. A magnet rotor :for an ignition magneto, said rotor comprising a' rotary magnet, separate pole shoes for said magnet, said pole shoes comprising a plurality of iron laminations, and interleaving plates made of non-magnetic material inserted at suitable intervals between the said ironlaminations, said interleaving lates each having a continuous periphery orming a bridge between the pole shoes and having an aperture for the insertion of the magnet suitably shaped to prevent the occurrence of lateral movement betweenvthe magnet and the pole shoes.

9. A magnet rotor for an ignition magneto, said rotor comprising a rotary magnet, separate pole shoes for said magnet, said pole shoes comprising a plurality of iron laminations, and interleaving plates inserted at suitable intervals between the said iron laminations, said pole shoes having slots therein and said magnet having its ends shaped to t into said slots in the pole shoes to prevent the occurrence of lateral movement between the magnet and the pole shoes.

10. A magnet rotor for an ignition magneto, said rotor comprisin a rotary magnet, separate pole shoes or said magnet, said ole shoes comprising a pluralit of iron aminations, and interleaving p ates made of non-magnetic material inserted at suitable intervals between the said iron laminations, said pole shoes having wedged shaped slots therein and said magnet having its ends shaped to {it into said slots in the pole shoes to prevent the occurrence of lateral movement between the magnet and the pole shoes.

11. A magnet rotor for an ignition magneto, said rotor comprisin a rotary magnet, separatepole shoes or said magnet, said pole shoes-comprising .a plurality of iron laminations, interleaving plates inserted at suitable intervals between the said iron laminations, and at least one balance weight to secure balance of the rotor about its axis of rotation.

12. A magnet rotor for an ignition magl neto, said rotor comprising a rotary niagnet, separate lpole shoes for said magnet, said pole shoes comprising a plurality of iron laminations, interleaving plates made of non-magnetic material inserted at suitable intervals between the said iron laminations, and at least one balance weight to secure balance of the rotor about its axis of rotation.

13. A magnet rotor for an ignition magneto, said rotor comprising a rotary magnet, separate pole shoes for said magnet, said pole shoes comprising a plurality of iron laminations of segmental shape, the arcs of said segmental shaped pole shoes subtending an angle of substantially less than 90 at the point constituting the centre round which the said arcs are described, and interleaving plates inserted at suitable intervals between the said iron laminations.

14. A magnet rotor for an ignition magneto, said rotor comprising a rotary magnet, separate pole shoes for said magnet, said pole shoes comprising a plurality of iron laminationsv of segmental shape, the arcs of said segmental shaped polel shoes subtending an angle of substantially less than 90 at the point constituting the center round which the said arcs are described, and interleaving plates made of non-magnetic material inserted at suitable intervals between the said iron laminations.

E. O. TURNER. E. B. TUPPEN. 

